The present invention concerns a multihull navigating structure with a variable operating mode.
In the maritime field, there are many navigating type structures each dedicated to one mode of operation, also depending on the distances to be covered.
The sphere of application of the present application more particularly concerns short and medium distances.
This is why there are boats for carrying passengers, more particularly ferry boats, river barges for transporting bulk materials, coasters with a plate for transporting containers or bulky elements occupying a large amount of space, and more rarely mixed units.
These boats have specific capacities which cannot be modulated according to needs.
Users are currently confronted with this disparity of needs during the course of time.
In fact, if one takes a ferry boat to carry out rapid rotations of passengers between a continent and an island for example, one can readily understand that the passenger traffic rate is more higher during the tourist season and that the requirements for raw materials, namely freight, are much greater during the rest of the year.
Similarly, as regards shorter cycles, one usage per day or at weekends can be anticipated and a different usage in the night or during the week.
When this type of boat is hired out from a company, the user can clearly specify his requirements and, according to the periods, rent various types of boats but the contracts shall be different with obviously higher prices.
The user, for example a local collectivity, can also provide the investment, but to ensure that this is profitable, he must either buy two types of boat or make the boat operate with an inadequate compromise between requirements and the possibilities of the boat.
No solution seems to be satisfactory, especially as the periods and requirements are generally approximately the same for the users of a given region.
It is also necessary to take into account maritime laws which are extremely constricting having regard to the environment on which the fleets are sailing.
These laws are much more restrictive when passengers are concerned.
Apart from the needs for the sufficient mechanical resistance of the structure in given circumstances, which is a basic obligation to obtain certification, it is proper to in particular provide all the required emergency exits to evacuate passengers, a partitioning of the engine room so as to separate the passenger compartments for obvious reasons of safety should a fire occur, as well as providing access for the boat personnel to the various rooms without there being an obligation to pass into one to reach another.
Similarly, even if certain constraints are not legally imposed, it is nevertheless essential to accept these so as to improve passenger comfort.
This is in particular the case with sanitary and ventilation installations.
There are also requirements common to all these boats: moving speed, low consumption, hence overall aerodynamics and seaworthiness.
There are boats for carrying passengers which generally include two hulls surmounted by a cell disposed for receiving passengers so as to form a motorised catamaran.
The cell forms an integral part of the structure and fully contributes in providing mechanical resistance of the unit.
Motorization is of the turbine and hydro-jet type so as to avoid increasing draft and drag and also is provided for safety reasons.
These boats move at high speeds but only have an extremely reduced freight capacity.